Recently, organic EL display devices have been progressively developed for decreasing the thickness, raising the luminance and increasing the operation speed of display panels. An organic EL display device is a display device including pixels formed of organic light-emitting diodes. The organic EL display device has high response speed because no mechanical operation is needed, is capable of providing high luminance display because each pixel itself emits light, and can have reduced thickness because a backlight unit is not needed. For these reasons, the organic EL display device is favorably expected to be a next-generation display device.
In such an organic EL display device, an organic EL light-emitting layer is rapidly deteriorated when being exposed to moisture and thus needs to be shielded against external air. Therefore, some conventional organic EL display devices have a structure in which a surface of the organic EL light-emitting layer is covered with a sealing film and bonded to a counter substrate, including color filters or the like, with a transparent resin being sandwiched between the organic EL light-emitting layer and the counter substrate (see, for example, Patent Literature 1, “Japanese Laid-Open Patent Publication No. 2001-338754”).
A conventionally known method for producing an organic EL display device having such a structure is as follows. As shown in FIG. 9, resins 4 and 5 are dripped onto a substrate 7, including an organic EL light-emitting layer, to form dot portions, and a counter substrate 6 is attached to the substrate 7 while the resins 4 and 5 are sandwiched between the substrates. The resins 4 and 5 are pushed and expanded, and are cured to bond the two substrates.
However, the above-described conventional method for producing the organic EL display device has the following problem. As shown in FIG. 10, the resin 5 is dripped to form a plurality of dot portions 5a, and the dot portions 5a are pushed and expanded by the step of attaching the substrate 7 and the counter substrate 6 to each other. As a result, the dot portions 5a adjacent to each other are fused together, and borders along which the dot portions 5a are fused together may appear as striped display irregularities 55z. As shown in FIG. 10, such display irregularities 55z are visually recognized as lattice-like display irregularities 55z, which may deteriorate the image quality of the organic EL display device.
In Patent Literature 1, the display irregularities 55z as shown in FIG. 10 are considered to be caused by stress that is generated when the resin 5 is cured and contracted. Thus, the organic EL display device described in Patent Literature 1 includes an organic film between the substrates 6 and 7 in order to alleviate the stress, in addition to the resin sealing film. However, such a structure enlarges the gap between the substrate 7 and the counter substrate 6. When the organic EL display device is observed in an oblique direction, light emitted by the organic EL light-emitting layer is not transmitted through a corresponding color filter but is transmitted through an adjacent color filter. This may cause color mixing in the pixels. In addition, the structure in which a plurality of layers are provided between the substrates 6 and 7 obstructs thickness reduction of the organic EL display device and size reduction of the pixels, and also may complicate the production steps and raise the production cost.